The specificity, capacity and control of amino acid transport are to be studied in mouse mammary gland in varying stages of development. In particular we plan to compare the properties of transport in tissue from virgin, pregnant and lactating normal glands with those of transport in hyperplastic nodules and tumors. The emphasis of our studies will be on a comparison of the characteristics of a recently described local feedback control mechanism in the various types of mammary gland. These studies may lead to a method of controlling growth of tumors by utilizing the properties of the local feedback control mechanism. BIBLIOGRAPHIC REFERENCES: Neville, M.C. & C. Lobitz (1977). Early events in the insulin stimulation of cell proliferation in pregnant mouse mammary gland. Fed. Proc. 36; P368. Neville, M.C. & C. Lobitz (1977). Control of amino acid transport in the mammary gland of the pregnant mouse. J. Supramolecular Struct. Suppl. 1:699.